class Solution {
public:
    double myPow(double x, int n) {
        return n<0 ? 1.0/pow(x,-(long long)n) : pow(x,n);
    }
    double pow(double x,long long n)
    {
        if(n==0)return 1.0;
        double tmp=myPow(x,n/2);
        return n%2==0 ? tmp*tmp : tmp*tmp*x;
    }
};
